1. Field of the Invention
The invention relates to a steering wheel having an airbag apparatus attached thereto, which has an airbag apparatus (airbag module) for protecting a driver from shock when the shock is applied to a vehicle such as automobile from a front thereof.
2. Related Art
In vehicles such as automobiles, it is necessary to protect a driver from shock when the shock is applied from a front due to a front end collision. Accordingly, a steering wheel configuring a part of a steering apparatus has been known in which an airbag apparatus (airbag module) is assembled in a pad of the steering wheel.
Regarding a structure that elastically engages the airbag apparatus to a core member configuring a frame of the steering wheel, a snap fit structure (snap lock mechanism) disclosed in Patent Document 1 has been known.
Specifically, as shown at least one of FIGS. 16A and 16B, a plurality of through-holes (insertion holes for mount pieces) 102 is formed in an axial direction (direction perpendicular to a sheet) along an axial line of a steering shaft at a plurality of positions of the core member 101. The airbag apparatus is provided with a plurality of pins (mount pieces) 104 protruding toward the core member 101, each of which has a recessed part 103 on an outer surface thereof. The pins (mount pieces) 103 are inserted into the through-holes (insertion holes for mount pieces) 102 when the airbag apparatus is elastically engaged to the core member 101.
An elastic wire (engaging spring) 105 made of spring steel and the like is moved in an assembling direction (direction parallel with the sheet) parallel with an orthogonal plane perpendicular to the axial line and then assembled to the core member 101. The elastic wire (engaging spring) 105 has an attaching part (parallel extending part) 106, an engaging part (parallel extending part) 107, a connecting part 108 and a pair of knobs 109. The attaching part (parallel extending part) 106 extends in the assembling direction and is attached to the core member 101. The engaging part (parallel extending part) 107 also extends in the assembling direction and is engaged to the recessed part 103 of the pin (mount piece) 104 in the through-hole (insertion hole for a mount piece) 102. The connecting part 108 connects one end portion of the attaching part (parallel extending part) 106 and one end portion of the engaging part (parallel extending part) 107. The knobs 109 are bent toward the axial line at each of the other end portion of the attaching part (parallel extending part) 106 and the other end portion of the engaging part (parallel extending part) 107. The knobs 109 are gripped when elastically deforming the attaching part (parallel extending part) 106 and the engaging part (parallel extending part) 107 so as to narrow an interval between the other end portions thereof.
The pin (mount piece) 104 inserted into the through-hole (insertion hole for a mount piece) 102 is elastically engaged to the metal core 101 as the engaging part (parallel extending part) 107 is engaged to the recessed part 103.
In the meantime, the core member 101 is provided with an assembly part 114 that extends in the assembling direction. The assembly part 114 has an axial restraint part 111, a surface restraint part 112 and a movement permission part 113. When assembling the elastic wire (engaging spring) 105 to the assembly part 114, the axial restraint part 111 permits the attaching part (parallel extending part) 106 to move and restrains the attaching part (parallel extending part) 106 engaged to the core member 101 from moving in the axial direction. When assembling the elastic wire (engaging spring) 105 to the assembly part 114, the surface restraint part 112 permits the attaching part (parallel extending part) 106 to move and restrains the engaged attaching part (parallel extending part) 106 from moving in a direction parallel with the orthogonal plane. A protrusion 112A, which configures a part of the surface restraint part 112, is provided on a path through which the attaching part (parallel extending part) 106 passes when it is linearly moved toward the assembly part 114, so that the protrusion restrains the engaged attaching part (parallel extending part) 106 from moving in an opposite direction to the assembling direction. When assembling the elastic wire (engaging spring) 105 to the assembly part 114, the movement permission part 113 permits the engaging part (parallel extending part) 107 to move.
The protrusion 112A of the surface restraint part 112 becomes an obstacle when linearly moving the attaching part (parallel extending part) 106 toward the assembly part 114. Accordingly, even when the elastic wire (engaging spring) 105 is arranged on the extension line of the assembly part 114 and is linearly moved in the direction parallel with the assembly part 114, it is not possible to assemble the elastic wire (engaging spring) 105 to the assembly part 114.
Thus, when assembling the elastic wire (engaging spring) 105 to the assembly part 114, the elastic wire (engaging spring) 105 is first arranged at a position that is offset from the assembly part 114, as shown in FIG. 16A. As shown with the dashed-dotted arrow in FIG. 16A, the elastic wire (engaging spring) 105 is moved in the assembly part 114 while changing a posture thereof so as to bypass the protrusion 112A. At this time, the movement of the attaching part (parallel extending part) 106 is permitted by the axial restraint part 111 and the surface restraint part 112. In addition, the movement of the engaging part (parallel extending part) 107 is permitted by the movement permission part 113.
When the elastic wire (engaging spring) 105 is moved to a position at which the attaching part (parallel extending part) 106 passes to the protrusion 112A, the axial movement of the attaching part (parallel extending part) 106 is restrained from moving in the axial direction by the axial restraint part 111 and the movement in the direction parallel with the orthogonal surface is restrained by the surface restraint part 112.
In the above descriptions about JP 2007-50876A, the names in the parentheses following the member names indicate the member names used in Patent Document 1.
However, in JP 2007-50876A in which the part (protrusion 112A) of the surface restraint part 112 is provided on the path through which the attaching part (parallel extending part) 106 passes when it is linearly moved toward the assembly part 114, the moving direction of the elastic wire (engaging spring) 105 should be changed when assembling the elastic wire (engaging spring) 105 to the core member 101, as described above. Therefore, it takes time to assemble the elastic wire (engaging spring) 105, so that the assembling time is prolonged.